There are many marginal oil wells which fail to produce a sufficient quantity of hydrocarbons to justify the continued expense of operation thereof. Once upon a time, most of these wells were considered good producers, especially when the wells were first completed; but over the years the hydrocarbon production declined until the wells no longer were considered economical to continue operation thereof. Usually the decline of hydrocarbon production is accomplished by a progressively increasing production of water. Often the water/oil production ratio will attain a value, for example, of two hundred barrels of water to twelve barrels of oil.
At other times, water production may remain fairly constant while the hydrocarbon production rate simply declines to an unacceptable value, which causes the operator to consider shutting the well in and salvaging the equipment therefrom.
Prior to abandoning the well, the operator will usually attempt to stimulate the well, as for example, a fracturing and acidizing process may be carried out on the old borehole. Occasionally the well fails to favorably respond to the fracturing treatment, and instead the well becomes a producer of excessive water, so that the operator now has a worthless well and an additional $75,000 to $100,000 investment in the stimulation treatment.
Therefore, it would be desirable to be able to isolate the water producing portion of a payzone so that the water/oil production rate is favorably improved, thereby avoiding the expense of producing water, as well as avoiding the expense of water disposal. A process which achieves this desirable goal is the subject of the present invention.